Writing instruments and self-pressurizing assemblies therefor



C. L. MALM Jan. 7,1969

WRITING INSTRUMENTS AND SELF-PRESSURIZING ASSEMBLIES THEREFOR Filed Aug.8, 1966 mmmmmmm e w a N s 60277: L MQLM United States Patent ()flicePatented Jan. 7, 1969 3,420,610 WRITING INSTRUMENTS AND SELF-PRES-SURIZING ASSEMBLIES THEREFOR Curtis L. Malm, Norwalk, Calif., assignorto Paper Mate Manufacturing Company, Santa Monica, Calif., a corporationof Delaware Filed Aug. 8, 1966, Ser. No. 570,824

US. Cl. 401-112 13 Claims Int. Cl. B431: 7/12 I ABSTRACT OF THEDISCLOSURE A unitary, replaceable ink-containing cartridge carrying aself-contained control assembly for normally venting the cartridge andpressurizing it during writing. The assembly includes a chamber with aresilient compression element, an actuating rigid member and springmeans normally venting the chamber and cartridge, movement of theactuating member against the spring causing the resilient element tocompress air in the chamber and cartridge. Writing instrumentscontaining such self-contained pressurizing cartridge.

Heretofore, there have been no commercially practical writinginstruments such as ball point pens which have been capable of sustainedwriting when the pen is oriented with its writing tip positioned otherthan in a generally downward direction from the ink supply or reservoirof the instrument. Thus, it :has not been possible to use suchinstruments to write on other than virtually horizontal surfaces, i.e.,not on steeply inclined or vertical surfaces and particularly not on theunderside of a horizontal surface. Bedridden individuals, particularlythose required to stay in a virtually horizontal position, have beeneffectively deprived of ability to write. This condition of the art incommercially mass-produced ball point pens results from dependence uponthe assistance of gravitational forces in delivering ink to the writingtip of the pen.

There have been various attempts in the prior art to apply additionalpressure to the ink supply to overcome this problem, however they havenot been particularly successful or commercially practical. These priorpressurizing devices have usually required special mechanism be builtinto the pen housing or barrel. Often the prior devices have beencomplicated and costly to manufacture. Further, they tend not to bedependable or durable under repeated use. The use of sealed cartridges,with a body of volatile gas at superatmospheric pressure above the inkresults in an expensive cartridge in which pressure may vary greatly,with resulting variation in writing ability.

A great variety of writing instruments is in use, most of them employinga cartridge which contains ink, such cartridge having a writing tip atone end and a rear end normally open to the ambient atmosphere. The tipsmay be permanently attached to the ink reservoir portion of thecartridge or removably attached. The cartridges vary in diameter, thoseof larger ink capacity being commonly called Jumbo." The barrels orhousings may or may not include project-retract mechanisms; thesemechanisms vary greatly.

The present invention provides a pressure control assembly which can bemade separately and readily and substantially irremovably installed inany prior or desired form of cartridge for use in any prior or desiredform of barrel or housing with any prior or desired form ofproject-retract mechanism. By the use of the present invention and itsnovel mode of operation, the writing instrument industry caneconomically attain a dependable instrument capable of continued writingon vertical surfaces without changes in ink characteristics or othertroublesome and expensive deviations.

An exemplary form of the present invention contemplates a replaceablecartridge which may be of essentially the same external dimensions as acustomary Jumbo refill or replacement, which cartridge is usable in thesame pen housing and with the same retracting mechanism as is thecustomary refill. The cartridge has an ink reservoir which is normally'vented at its rear to the atmosphere as in the case of the customaryrefill. Normal writing pressure on the writing tip of the cartridgedepresses it a slight or nominal amount, which movement is sufficienthowever to close the atmospheric vent to the ink reservoir and to causean elastic and resilient pressure element to be deformed so as to trapand compress the air in the reservoir and exert a small added pressureupon the ink in the reservoir. This permits easy free flowing andcontinuous writing with the pen, particularly on vertical or upside downsurfaces. The pressurizing mechanism is contained in the cartridgeitself, which, as noted above, is of usual size and configuration foruse with usual pen housings and retraction mechanisms. The movement ofthe tip during writing is very small, on the order of 0.01" to 0.06",and normally not observed during use of the writing instrument.

Accordingly, it is an object of the present invention to provide a noveland improved construction of writing instrument.

Another object of the present invention is to provide a novel andimproved writing instrument and/or cartridge of a kind which ispressurized automatically by normal writing pressure on the writing tipof the instrument, for providing increased writing capability andparticularly for permitting continuous Writing on surfaces that areother than substantially horizontal.

It is another object of the invention to provide a novel and improvedcompact pressure control assembly for a writing cartridge.

It is another object of the present invention to provide A such anautomatically pressurizing cartridge of essentially the same size andconfiguration as a customary Jumbo refill for use as a replacement forsuch a refill.

It is a more specific object of the present invention to provide such anautomatically pressurized device having an elastic, resilient elementwhich is deformed by slight movement produced by writing pressure on thetip of the device.

A further object of the present invention is to provide a novel andimproved automatically self-pressurizing writing instrument and/orcartridge which is relatively easy and economical to manufacture andassemble and which is durable and dependable in operation.

Other objects and advantages of the present invention will become moreapparent from the following description in the associated drawings,wherein:

FIG. 1 is a longitudinal sectional view of a retractable ball point penembodying various features of the present invention, the cartridge ofthe illustrated pen being shown in projecting, non-writing position;

FIG. 2 is an enlarged longitudinal section to reveal details of interiorconstruction, of the upper portion of the cartridge of the pen shown inFIG. 1, said upper portion incorporating a pressure control assemblyWhich is shown in projecting, non-writing position;

FIG. 3 is a view like FIG. 2, showing the position of the control meansunder pressure during writing;

FIG. 4 is a sectional view of a modified form of pressure controlassembly in a cartridge shown in non-writing position;

FIG. 5 is a view like FIG. 4, but with the pressure control assemblyshown in writing position.

One exemplary form of writing instrument of the present invention isshown in FIGS. 1 through 3 as a ball point pen 1. The pen 1 is shown ina vertically extending position and will be described in that positionas a matter of convenience, it being understood that a pen embodying thepresent invention may be used in other positions such as horizontallyextending and even with its writing tip uppermost. The illustrated pen 1comprises a hollow housing or barrel 2 for a self-contained,automatically-pressurizing cartridge 10. While the cartridge may bepermanently encased within a barrel, the illustrated barrel 2 is formedof upper and lower halves which are threadedly connected so that theycan be separated to permit replacement of the cartridge. Further, whilethe pen may 'be of the kind in which the writing tip is permanentlyexposed, the illustrated pen is of the re tractable type, of which thereare a great variety. The cartridge 10 is movable longitudinally of thehousing 2 to an extended position as shown in FIG. 1 with a writing tip4 at the forward end of the cartridge extending through an opening inthe end of the barrel. A coil retraction spring 5 disposed around theforward end of the cartridge urges it rearwardly to a retracted position(not shown).

Various dilferent retract-project mechanisms could be used; FIG. 1illustrates one exemplary form of such a mechanism, which is designatedgenerally at 3 and which is generally as shown and described in detailin United States Letters Patent No. 2,941,510.. Very broadly, theretract-project mechanism 3 is operated by a depressible plunger 6 atthe rear end of the pen to alternately and sequentially move thecartridge between the extended and retracted positions. Depressing theplunger 6 alternately supports a cam follower 7, which is in engagementwith the upper end of the cartridge 10, on first a forward shoulder 8and then a rearward shoulder 9. As shown in FIG. 1, when a forwardshoulder 8 is supporting the cam follower 7, the cartridge is held inthe extended Writing position against the retraction spring 5.

As noted above, the cartridge 10, while it may be permanently installedor enclosed in the barrel, is illustrated as a replaceable cartridgewhich may be used to replace a used or defective prior cartridge of thesame or other construction. The overall size and configuration of theillustrated cartridge 10 generally 'is the same as that of thecustomaryJumbo refill, although other sizes and configurations may be used; thissize and configuration is desirable in that it ordinarily permits theuse of the cartridge with pens adapted to accommodate such Jumbo refillswhile providing more space for a pressure control assembly than would beprovided in a thinner standard-size refill. As also noted above, thecartridge may be used in non-retractable as well as retractable pens.

The cartridge 10 shown in FIG. 1 includes an elongated generallycylindrical tube or casing 12 which comprises a tubular reservoir ofvirtually uniform diameter for containing a supply of ink (FIG. 2). Thecartridge 10 also has a pressure control assembly or means 20 mounted atthe rear end of the reservoir 12. The forward end portion 14 of thereservoir 12 which is narrowed, supports the writing tip 4 at itsforwardmost end in communication with the ink in the reservoir. As shownin FIG. 2, a grease follower 16 may be disposed across the reservoir 12rearwardly of the ink supply 14 to follow the rearward end of the inksupply forwardly as the ink is used.

The pressure control assembly 20 may be produced separately forinstallation in the rearward end of a reservoir. Once it is installed,it becomes a relatively permanent or integral irremovable part of thecartridge. It operates, incident to writing pressure being applied tothe writing tip, to exert a relatively low magnitude pressure force tothe rear of the ink supply in the reservoir. This low pressure avoidsleakage problems at the tip which could result from high cartridgepressure. It will be noted that the pressure control assembly 20 isquite compact so that it does not appreciably increase the length orwidth of the cartridge and does not require a large diameter barrel overthat of the customary Jumbo size refill and does not require a reductionin the amount of ink held by the cartridge.

The assembly 20 comprises a cup-shaped adapter 22 including a generallycylindrical side wall 24, a bottom or forward. end wall 26 provided witha central port 28, and stop flange means 30 at the open end of theadapter. The adapter 22 is preferably arranged for installation into theopen rear end of the reservoir 12 by a press fit. The adapter may be ofone piece (as shown in FIGS. 4 and S), or may be of two pieces as shownin FIGS. 2 and 3, wherein it includes a generally cylindrical metalouter section 32 and an interlocked cup-shaped plastic composition innersection 34.

Referring more particularly to FIGS. 2 and 3, the adapter outer section32 has its rear edge turned outwardly to form the stop flange means 30,which engages and overlies the rear edge of the reservoir 12. Theforward edge of the adapter outer section 32 is turned inwardly to forman annular locking flange that is received in an annular groove aroundthe adapter inner section 34. The adapter 22 forms a central pressurechamber or compartment 36 having its rearward end enlarged to provide areceptacle portion for receiving an elastic, resilient pressure element.The chamber has a rearwardly directed annular retaining contact face 38at the forward end of the receptacle portion and an annular inwardlyextending sealing seat or shoulder 40 surrounding the rearward end ofthe receptacle portion.

The assembly 20 also includes a loosely fitting generally cylindricalpiston 50 supported for limited relative axial movement within the openrear end of the cup-shaped adapter 22. A retaining rod or stem 52connected to the forward end of the piston 50 extends loosely throughthe port 28 of the adapter and limits such movement of the piston 50.The piston 50 and stem 52 are provided in the exemplary embodiment ofFIGS. 1 to 3 as integral parts of a movable member which also includesan integrally formed rear portion 54 having a forwardly directed annularstop shoulder 56 at the rear end of the piston 50 which can engage theflange 30 of the adapter to limit forward movement of the piston. Afterthe stem 52 is forced through port 28, circumferentially spaced ears 58at the forward end of the stem 52 provide means for limiting rearwardmovement of the piston 50. Various other movement limiting means couldalso be used.

The assembly 20 also includes biasing means provided within the adapter22 for normally biasing the piston 50 rearwardly. In the exemplaryembodiment of FIGS. 1 to 3, the biasing means is provided by a coilpressure control spring 60 disposed around the stem 52. The pressurecontrol spring 60 urges the piston 50 rearwardly relative to the adapter22 and to the reservoir 12 to the position shown in FIG. 2. If desired,other forms of springs may be used.

The pressure control spring 60 is stronger than the retraction spring 5so that the depression of the plunger 6 against the cartridge 10 willcompress the rertaction spring 5 without compressing the control spring60. For example, the pressure spring may require about an 8 oz. forcefor its compression while the retraction spring may require only about a6 oz. force. The differential force between the retraction spring 5 andthe pressure control spring is preferably between about 1 ounce and 5ounces. Thus, the cartridge 10 may be put in its extending writingposition as shown in FIG. 1, and the pressure control assembly 20remains in its non-compressed condition as shown in FIG. 2.

The pressure control assembly 20 further comprises a resilient andelastic element or means actuated by movement of the piston 50 againstthe biasing means 60 for expelling air from the adapter through thecenter port 28. In one exemplary embodiment (FIGS. 1 to 3), theresilient means is provided by a tflat circular disc or washershapedelement 70 while in another embodiment (FIGS. 4 and 5), the resilientmeans is provided by a hollow cylindrical element 70a. The washer shapedelement 70, which is made of rubber or various elastomeric materials, isdisposed around the upper portion of the stem 52 between the rear end ofthe spring 60 and the forward end of the piston 50. The washer-shapedelement 70- has a smaller diameter than the internal diameter of theadapter 22 to provide clearance and a passage for air. The diameter ofthe washer-shaped element 70 is somewhat larger than that of the rearend of the receptacle portion of the pressure chamber 36 so that theelement engages the seal seat 40 at the entrance to the receptacleportion and is flexed or deformed when the element is moved into thereceptacle portion and contact face 38. The washer-shaped element 70 isdesirably quite thin, having for example a thickness of from about 0.02to about 0.06 inch. The element is preferably of moderate hardness,having for example a hardness of from about 30 to about 60 durorneters.Thus, when not subjected to writing pressure, as shown in FIG. 2 andindicated by the arrows, there is a vent passage for air flow providedby the annular space between the piston 50 and the adapter 22, by theannular space between the washer-shaped element 70 and the adapter 22,by the annular opening between the lower edge of the washer-shapedelement 70 and the shoulder 40 of the adapter, by the pressure chamber36, and by the space between the lower end of the stem 52 and the port28.

The operation of the ball point pen 1 may now be readily understood. Theplunger 6 is depressed to move the cartridge against the retract spring5 into extended writing position as shown in FIGS. 1 and 2. As notedabove, the pressure control spring 60 is stronger than the retractspring 5 so that the control spring 60 is not compressed at this time.The cartridge 10 is locked in this extended position by the cam follower7 abutting rearwardly against a forward shoulder 8 and the rear portion54 of the movable element abutting the cam follower to prevent rearwardmovement of the piston 50. Now when the writer begins to write with thepen 1 and applies normal pressure on the writing tip 4, the reservoir 12and the adapter 22 are moved rearwardly relative to the restrainedpiston 50 and washer-shaped element 70. Incident to this relativemovement, initially the shoulder 40 at the entrance to the receptacleportion of the chamber engages the underside periphery of thewasher-shaped element 70 to close the vent passage between the reservoirrear and the ambient atmosphere. Then the elastic, resilientwasher-shaped element 70 is deformed and received into the receptacleportion (FIG. 3) to reduce the volume of the pressure chamber 36 andforce air outwardly through the port 28 to the rear end of the reservoir12. This serves to apply a relatively small increment of additionalpressure to the rear of the ink supply 14. This pressure may be on theorder of a fraction of an ounce. When the writing pressure on the tip 4is released, the parts will return generally to their positions shown inFIG. 2, with the pressure chamber 36 and the upper end of the reservoir12 being returned to a communication with ambient pressure. Subsequentapplications of writing pressure will each impart a relatively lowpressure surge or force to the rear of the ink supply so that pressureis automatically applied incident to the use of the pen. As previouslystated, the springs are designed to keep the cartridge vented both inretracted and projecting positions and to respond to a writing pressureof between 1 and 5 ounces to cause pressurization.

The annular shoulder or surface 56 provides means which prevent thepiston 50 from moving too far forwardly into the adapter 22 to deformthe elastic element 70 beyond its elastic limit.

Various modifications and changes may be made in the exemplaryembodiment of FIGS. 1 to 3 without departing from the spirit and scopeof the present invention. For example, but not by way of limitation,FIGS. 4 and 5 show a modified form of the pressure control assembly200:. Comparable elements are designated in general by the same numberwith an a sufiix.

Referring to FIG. 4, the assembly 20a includes the cup-shaped metaladapter 22a, which has a cylindrical side wall 24a and forward end wall26a with a central vent port 28a. The adapter 22a is press fit into therear open end of the reservoir 12 and the rear edge of the adapter isturned outwardly to provide a stop flange 30a which engages and restsupon the upper edge of reservoir. The assembly 20a also includes acylindrical piston 50a loosely fit in the adapter 22a for limited axialmovement. A stem 52a extends forwardly from the piston loosely throughthe port 28a and is provided with circumferentially spaced ears 58a tolimit rearward movement of the piston 50a. The piston 50a and the stem52a are provided, in the exemplary embodiment of FIGS. 4 and 5, asintegral parts of a movable member which also has a rear portion 54ahaving an annular forwardly facing shoulder 56a. The shoulder 56a is atthe rear end of the piston and is adapted to engage the stop flange 30ato limit forward movement of the piston 50a. This serves to protect theresilient elastic means from being deformed beyond its elastic limit.

The assembly 20a also includes biasing means in the form of a coiledpressure spring 60a disposed around the stern 52a between the piston 50aand the adapter 22 to urge the piston 50a relatively rearwardly. Theassembly 20a further includes an elastic, resilient deformable elementor means in the form of a hollow cylindrical barrel or sleeve 70a ofrubber or an elastomeric material. The sleeve 70a is disposed generallycoaxially within the adapter 50a and secured at its upper end around anenlarged cylindrical hub portion at the base of the stem 52a. A pressurechamber 36a is defined within the deformable sleeve 70a. The outerdiameter of the sleeve 70a is approximately the same as that of thepiston 50a, with the outer diameters of both being somewhat smaller thanthe inner diameter of the adapter to provide an air passagetherebetween. The parts are proportioned as shown in FIG. 4 so thatthere is also normally an air passage between the forward end of thesleeve 70a and the end wall 26a of the adapter. Thus, with the pen partsin non-writing position (FIG. 4), a vent passage is provided between theflange 30a and the shoulder 56a, between the adapter side wall 24a andthe piston 50a and sleeve 70a, between the adapter end wall 26a and theforward end of the sleeve, and through the port 28a around the stem 52a.This places the rear of the reservoir 12 in communication with theambient atmosphere.

Normal writing pressure on the pen tip 4 moves the reservoir 12 and theadapter 22a rearwardly toward the position shown in FIG. 5, relative tothe piston 50a and and the elastic sleeve 70a. First the end wall 26a ofthe adapter engages the lower end of the sleeve 70a which blocks the airpassage from the atmosphere to the pressure chamber 36a and to the endof the ink reservoir 12; further rearward movement of the adapterrelative to the piston deforms the sleeve 70a by bowing its centralportion inwardly (FIG. 5) so as to reduce the volume of the pressurechamber 36a and exert a small amount of pressure through the port 28aagainst the rear of the ink supply 14 in the reservoir 12.

Thus, there have been described several exemplary forms of simplecompact and economical self-contained ink-containing cartridges for usein a pen to automatically pressurize the ink supply of the cartridge bywriting with the pen. A pressure control assembly for the cartridge iscompactly constructed and adapted to be relatively permanently assembledwith an ink reservoir. The reservoir may be of a usual or customary sizeand configuration and the compact assembly is such that, when it ismounted on the reservoir, the resultant cartridge is not appreciablylonger or wider than a customary cartridge of that style; therefore, thecartridge may be utilized to replace a customary non-pressurizingcartridge. Generally, the same ink capacity is also maintained. Also,the ink supply is normally vented to the atmosphere so that no partialvacuum results from repeated pressuring of the reservoir, which partialpressure could impair the ink flow to the writing tip.

Another advantage of the present invention is that pressure generated inthe cartridge is kept relatively low; a Writing tip designed to operateat atmospheric pressure would tend to leak or gob around the ball whenthe cartridge pressure is high. This invention takes advantage of thefact that the writing instrument is raised and lowered from the paperliterally thousands of times while writing a single page, and at eachapplication of the tip to the paper, a small pressure impulse isgenerated, tending to move the body of ink toward the tip. Moreover, theeffect of a pressure impulse is not dissipated instantaneously uponraising of the writing tip (out of contact with the paper); the mode ofoperation utilizes the heretofore ignored elastic hysteresis, relaxationand elastic after effects of the elastomeric materials used, andalthough these effects are of a low order of magnitude, they assist inthe attainment of the objects of this invention.

Another advantage of the invention is that the writing tip is moved ordisplaced only a slight amount when writing pressure is applied. Thisdoes not interfere with the use of the pen and is generally notperceptible to the user except as a slight give or cushioning effectwhen the pen tip is applied to the paper. The tip movement, which is thesame as the relative movement of the resilient means to first close thereservoir from the atmosphere and then occupy a small portion of thepressure chamber, is kept small because it is not necessary (ordesirable) to apply high pressure to the reservoir; thus, smallmovements provide the desired pressure surges.

Various features of the invention are set forth in the following claims.

I claim:

1. A pressurizing control assembly for installation at the rear end ofan ink reservoir of a writing instrument, comprising:

a hollow, cup-shaped adapter having side walls, a centrally portedbottom and stop flange means at the open end thereof, said adapter beingarranged for installation into the open end of an ink reservoir;

an axially movable, loosely fitting piston in the open end of theadapter, said piston being provided with a stem extending through theported bottom of the adapter;

means within the adapter normally biasing said piston outwardly andmeans carried by the piston stem limiting said outward movement;

and resilient, elastic means actuated by movement of the piston againstsaid biasing means for expelling air from said adapter through saidbottom port into the rear end of the ink reservoir of the writinginstrument.

2. A pressurizing control assembly as stated in claim 1, including meansfor limiting the inward movement of the piston against the biasingmeans.

3. A pressurizing control assembly as stated in claim 1, wherein theinterior of said adapter is in communication with ambient air past saidpiston and with said bottom port when said piston is at the outwardlimit of its movement,

and communication between the interior of said adapter and ambient airpast said piston is discontinued when said piston is moved against saidbiasing means.

4. A pressurizing control assembly as stated in claim 1, wherein theadapter includes an inwardly extending shoulder, and

the elastic means is carried by the stern and said piston moves theelastic means into contact with said shoulder when said piston is movedagainst said biasing means.

5. A writing instrument having a replaceable unitary self-contained,ink-containing cartridge that is adapted to automatically apply pressureto the ink incident to use of a writing instrument, said writinginstrument comprising:

a hollow barrel;

a cartridge supported in said barrel and including a tubularink-containing reservoir having a writing tip at its forward end and apressure control assembly attached to and extending into and rearwardlybeyond the rear end of the cartridge, said pressure control assemblyincluding a cup-shaped adapter, a rigid member carried by the adapterfor limited axial movement, spring means normally biasing said memberrearwardly into a position in contact with the rear of said barrel andventing the rear portion of the reservoir to ambient atmosphere, andelastic, resilient means within the assembly, actuated by forwardrelative movement of the member with respect to the reservoir, adaptedto isolate the rear portion of the reservoir from ambient atmosphere andincrease the pressure Within such rear portion.

6. A unitary self-contain6d pressurizing ink cartridge for a Writinginstrument, said cartridge comprising:

(a) an ink supply tube having a forward end and a rearward end anddefining an ink reservoir in communication with said ends,

(b) a writing tip at the forward end of said tube, and

(c) a pressure control assembly mounted on the rearward end of saidtube, said pressure control assembly including (1) a generallycup-shaped adapter that is secured in the rearward end of said tube anddefines a pressure chamber having an enlarged receptacle at its rearwardend, said cup-shaped adapter opening rearwardly to define an inlet tosaid pressure chamber in communication with the atmosphere, said inletincluding a rearwardly facing annular shoulder surrounding said inletand located at the rear of said compressor receptacle, said cup-shapedadapter having a center port at its forward end providing an outlet fromsaid chamber to said rearward end of said tube,

(2) a compressor piston axially slidable in the open rearward end ofsaid cup-shaped adapter with radial clearance between said piston andsaid adapter for normally venting said ink reservoir, said piston havinga stem generally centered within said tube and extending through saidcentral port with radial clearance between said port and said stem,

(3) a deformable elastic and resilient fiat ringshaped element disposedaround said stem between the forward end of said piston and said annularshoulder with radial clearance between said elastic element and saidadapter, said elastic element extending radially outwardly of saidreceptacle shoulder,

(4) a coil spring disposed around said stern between said deformableelement and the forward end of said cup-shaped adapter urging saidpiston and said elastic element rearwardly relative to said adapter andsaid tube, and

(5) means on said stem for engaging said adapter to limit said relativerearward movement of said elastic element and said piston to a positionaffording axial clearance between said deformable element and said inletshoulder, whereby rearward pressure on said writing tip incident tonormal writing will tend to compress said spring, engage said shoulderwith said elastic element, and deform said elastic element into saidcompressor receptacle to reduce the volume of said pressure chamber andapply pressure to the rear of said ink reservoir.

7. A self-contained, adaptable and unitary ink-containing cartridgeadapted for use in a hollow writing instrument barrel and arranged toautomatically increase the pressure of an atmosphere above a body of inkin such cartridge during writing, comprising:

a tubular cartridge of virtually uniform diameter having a writing tipof smaller diameter at its forward end in communication with a body ofink within the cartridge and an atmosphere in the rear end portion ofthe cartridge and rearwardly of said ink;

and a pressure control assembly attached to said cartridge at its rearend, said control assembly including:

a ported wall disposed within said cartridge adjacent its rear end;

a virtually rigid member mounted for limited axial movement looselyextending through said ported wall and extending into said cartridge andhaving a head end extending rearwardly beyond the open end of thecartridge;

an elastic, resilient element within said assembly for movement withsaid member, said resilient element being disposed rearwardly of saidported wall,

and a spring means normally biasing the member rearwardly to place theatmosphere in the rear portion of the cartridge in communication withatmosphere ambient the cartridge, axial movement of said member againstsaid biasing spring and with respect to the cartridge actuating theelastic element to compress the atmosphere within the cartridge.

8. A cartridge as defined in claim 7 wherein the assembly includes acup-shaped adapter inserted into the rear end of the cartridge, saidadapter having a ported bottom and side walls including an inwardlyextending, rearwardly facing annular contact face,

and the elastic resilient element is a disc Whose edge portionscooperate with said contact face to compress the atmosphere within thecartridge.

9. A cartridge as defined in claim 7, wherein said pressure controlassembly includes 'a pressure chamber and the elastic element isgenerally tubular and providing a side wall of said pressure chamber andadapted to deform radially incident to being axially compressed by therigid member to reduce the volume of said chamber.

10. In a retractable writing instrument including a rear :barrel portioncarrying a manually operable projectretract mechanism, a front barrelportion having a forward opening adapted to receive the writing tip of areplaceable ink-containing cartridge, a replaceable ink-containingcartridge having a main tubular body ink reservoir portion of virtuallyuniform diameter provided with an open rear end and a forward extensionof smaller diameter terminating in a Writing tip, and a retractionspring in the forward barrel portion normally biasing the cartridge intoa retracted position against said project-retract mechanism, theprovision of:

a pressure control assembly attached to and extending into the open rearend of the main body portion, said assembly including a cup-shapedadapter having a centrally ported bottom, an axially movable looselyfitting piston element on the adapter and extending rearwardlytherefrom, said piston being provided with a stem loosely extendingthrough the centrally ported bottom;

spring means within the adapter normally biasing said piston outwardlywhereby the ink reservoir portion may be vented through said portedbottom and around said piston to ambient atmosphere;

and resilient elastic means carried by said stern and actuated bymovement of the piston against said biasing spring for compressing airwithin said adapter for movement through said ported bottom into the inkreservoir;

the force of said biasing spring exceeding the force of the retractingspring whereby the self-venting and pressurizing cartridge may be movedby the projectretract mechanism and remain vented in both projected andretracted positions of the cartridge.

11. In a retractable writing instrument including a rear barrel portioncarrying a manually operable projectretract mechanism, a front barrelportion having a forward opening adapted to receive the writing tip of areplaceable ink-containing cartridge, a replaceable ink-containingcartridge having a main tubular body ink reservoir portion of virtuallyuniform diameter provided With an opening rear end and a forwardextension of smaller diameter terminating in a writing tip, and aretraction spring in the forward barrel portion normally biasing thecartridge into a retracted position against said projectretractmechanism, the provision of:

a pressure control assembly attached to and extending into the open rearend of the main body portion, said assembly including a cup-shapedadapter having a centrally ported bottom, an axially movable looselyfitting piston element on the adapter and extending rearwardlytherefrom, said piston being provided with a stem loosely extendingthrough the centrally ported bottom;

stop means carried by the stem for cooperation with the bottom to limitoutward axial movement of said stem and piston element;

spring means Within the adapter normally biasing said piston outwardlywhereby the ink reservoir portion may be vented through said portedbottom and around said piston to ambient atmosphere;

and resilient elastic means carried by said stem and actuated bymovement of the piston against said biasing spring for compressing airwithin said adapter for movement through said ported bottom into the inkreservoir.

12. A writing instrument as stated in claim 11 wherein the resilient,elastic means comprise a washer of rubberlike material and the edgeportion of said Washer is deformed by contact with said adapter tocompress air when said piston is moved with respect to the cartridge bywriting pressure upon the tip thereof.

13. In a retractable writing instrument including a rear barrel portioncarrying a manually operable projectretract mechanism, a front barrelportion having a forward opening adapted to receive the writing tip of areplaceable ink cartridge, and a retraction spring in the front barrelportion normally biasing the cartridge into a retracted position againstsaid project-retract mechanism, the provision of:

a tubular cartridge of virtually uniform diameter having a writing tipof smaller diameter at its forward end in communication with a body ofink within the cartridge and an atmosphere in the rear end portion ofthe cartridge and rearwardly of said ink;

and a pressure control assembly attached to said cartridge at its rearend, said control assembly including;

a ported wall disposed within said cartridge adjacent its rear end;

a virtually rigid member mounted for limited axial movement looselyextending through said ported wall and extending into said cartridge andhaving a head end extending rearwardly beyond the open end of thecartridge;

an elastic, resilient element within said assembly for movement withsaid member, said resilient element being disposed rearwardly of saidported wall;

and a spring means normally biasing the member rearwardly to place theatmosphere in the rear portion of the cartridge in communication withatmosphere ambient the cartridge, axial movement of said member againstsaid biasing spring and with respect to 1 1 the cartridge actuating theelastic element to compress the atmosphere within the cartridge.

References Cited UNITED STATES PATENTS 2,870,742 1/1959 Hackmyer 4011453,113,558 12/1963 Marrafiino 401-187 3,139,864 7/1964 Henriksen 401187 12 FOREIGN PATENTS 167,758 8/ 1950 Austria. 995,271 8/ 1951 France.1,191,405 4/1959 France.

LAWRENCE CHARLES, Primary Examiner.

US. Cl. X.R. 401188

